Volume 0,Issue 8,2003 Table of Contents
2003(8):577-584.
Abstract:
Current situation and prospect for titanium industry in America, Japan and China is briefly reviewed. Chracteristics in aspects of Ti resources, production of Ti sponge and Ti materials, Ti application development, research and development of Ti alloys, are compared.
Current situation and prospect for titanium industry in America, Japan and China is briefly reviewed. Chracteristics in aspects of Ti resources, production of Ti sponge and Ti materials, Ti application development, research and development of Ti alloys, are compared.
2003(8):585-590.
Abstract:
结合相关的理论基础，综述了超声化学制备纳米材料的研究进展。主要涉及采用和发展多种前驱物声化制备无机纳米材料，特别是超声电沉积法制备纳米粉体新技术及超声制备无机-有机纳米复合材料等的进展；并展望了今后的研究方向。
结合相关的理论基础，综述了超声化学制备纳米材料的研究进展。主要涉及采用和发展多种前驱物声化制备无机纳米材料，特别是超声电沉积法制备纳米粉体新技术及超声制备无机-有机纳米复合材料等的进展；并展望了今后的研究方向。
2003(8):591-595.
Abstract:
Microstructure modeling of aluminum alloy castings has been carried out by using a new stochastic modeling methods coupled with macro heat transfer calculations. The actual dendritic shape is substituted for the square envelope in the cellular automaton model. A physical model and a mathematical model for the simplified dendrite shape are established in the paper, in which a shape function is presented to describe the dendrite shape contour. On the basis of the simplified grain shape, a coordinate transformation method is used to describe the equiaxed grain growth in the undercooled melts and the node capturing during the further growth of a grain. A continuous nucleation model is applied to deal with heterogeneous nucleation phenomenona. Dendrite tip growth kinetics and preferential <100> crystallographic orientation are taken into account. The stochastic nature of nucleation process as well as the deterministic of dendrite growth is considered to simulate the crystal growth. A microstructure simulation scheme is developed to model the grain formation according to the above model. Two- dimensional calculations are performed to simulate the evolution of equiaxed dendritic morphologies. In order to verify the modeling results, sample castings are cast in sand molds and metal molds. Simulation results show that grain size is smaller for metal mold casting, but larger for sand mold casting, in good agreement with both the experimental results and the postulated solidification mechanism.
Microstructure modeling of aluminum alloy castings has been carried out by using a new stochastic modeling methods coupled with macro heat transfer calculations. The actual dendritic shape is substituted for the square envelope in the cellular automaton model. A physical model and a mathematical model for the simplified dendrite shape are established in the paper, in which a shape function is presented to describe the dendrite shape contour. On the basis of the simplified grain shape, a coordinate transformation method is used to describe the equiaxed grain growth in the undercooled melts and the node capturing during the further growth of a grain. A continuous nucleation model is applied to deal with heterogeneous nucleation phenomenona. Dendrite tip growth kinetics and preferential <100> crystallographic orientation are taken into account. The stochastic nature of nucleation process as well as the deterministic of dendrite growth is considered to simulate the crystal growth. A microstructure simulation scheme is developed to model the grain formation according to the above model. Two- dimensional calculations are performed to simulate the evolution of equiaxed dendritic morphologies. In order to verify the modeling results, sample castings are cast in sand molds and metal molds. Simulation results show that grain size is smaller for metal mold casting, but larger for sand mold casting, in good agreement with both the experimental results and the postulated solidification mechanism.
2003(8):596-599.
Abstract:
To study the effect of substrate materials on the texture of magnetron sputtered indium, the UBM(Under Bump Metallization) of Cr/Au film, single crystal (111) InSb and amorphous photoresist were employed as substrate materials. The results indicate that the patterns of the indium textures are almost independent of the substrate materials, and the texture components consist of a strong (101) fiber texture and a weak (110) fiber texture. The texture mode proves that the texture forming mechanism of indium is a growth competition phenomenon.
To study the effect of substrate materials on the texture of magnetron sputtered indium, the UBM(Under Bump Metallization) of Cr/Au film, single crystal (111) InSb and amorphous photoresist were employed as substrate materials. The results indicate that the patterns of the indium textures are almost independent of the substrate materials, and the texture components consist of a strong (101) fiber texture and a weak (110) fiber texture. The texture mode proves that the texture forming mechanism of indium is a growth competition phenomenon.
2003(8):600-603.
Abstract:
根据Kohler三元溶体模型和Miedema二元系统生成热模型，建立了计算三元合金及金属间化合物各组分活度系数的方程，不仅能处理三元合金及金属间化合物体系，也能处理二元系，甚至可以近似处理多元系。计算了Ti-5Al-2．5Sn，Ti-6Al-4V，Ti-25V-15Cr-0．2Si及TiAl中各组分的活度系数并与有关实验值进行对比，发现根据本研究公式计算的结果比非对称计算公式获得的结果更符合实际。将计算结果应用于钛基复合材料的界面反应研究，可以预测到：SiC／Ti-6Al-4V基复合材料的界面反应较严重，SiC／Ti-25V-15Cr—0．2Si的界面反应较难进行，SiC／TiAl的界面反应程度最轻。
根据Kohler三元溶体模型和Miedema二元系统生成热模型，建立了计算三元合金及金属间化合物各组分活度系数的方程，不仅能处理三元合金及金属间化合物体系，也能处理二元系，甚至可以近似处理多元系。计算了Ti-5Al-2．5Sn，Ti-6Al-4V，Ti-25V-15Cr-0．2Si及TiAl中各组分的活度系数并与有关实验值进行对比，发现根据本研究公式计算的结果比非对称计算公式获得的结果更符合实际。将计算结果应用于钛基复合材料的界面反应研究，可以预测到：SiC／Ti-6Al-4V基复合材料的界面反应较严重，SiC／Ti-25V-15Cr—0．2Si的界面反应较难进行，SiC／TiAl的界面反应程度最轻。
2003(8):604-606.
Abstract:
The electrical resistivity of the composite MoSi2 SiC containing various SiC contents was calculated by a topological method. The results of theory and experiment were found to be in good agreement. The researching results indicate that the electrical resisitivity of the bulk composite can be increased by increasing the volume fractions of the higher resistivity SiC phase and reducing continuity of the MoSi2. The approach described may predict the SiC volume fractions and microstructures needed to obtain some desired electrical resistivity, and may provide insights into the final microstructure.
The electrical resistivity of the composite MoSi2 SiC containing various SiC contents was calculated by a topological method. The results of theory and experiment were found to be in good agreement. The researching results indicate that the electrical resisitivity of the bulk composite can be increased by increasing the volume fractions of the higher resistivity SiC phase and reducing continuity of the MoSi2. The approach described may predict the SiC volume fractions and microstructures needed to obtain some desired electrical resistivity, and may provide insights into the final microstructure.
2003(8):607-609.
Abstract:
A convection/diffusion single phase governing equation was employed to deal with heat transfer and fluid flow in solid, solid liquid and liquid phase system in a description of melting and solidification. A source term method was used to deal with changes of momentum and energy in respective governing equations. Based on commercial software Phoenics which is very useful in fluid flow and heat transfer, several modules were added. A 3 D transient temperature field and velocity field simulation program was developed and used to describe the laser cladding synthesis TiCp/Al composite material. A ZL104 specimen was taken as an example, to clad TiCP/Al composite by laser and to calculate the process with the developed program. Calculated results were basically coincident with those measured in the experiment.
A convection/diffusion single phase governing equation was employed to deal with heat transfer and fluid flow in solid, solid liquid and liquid phase system in a description of melting and solidification. A source term method was used to deal with changes of momentum and energy in respective governing equations. Based on commercial software Phoenics which is very useful in fluid flow and heat transfer, several modules were added. A 3 D transient temperature field and velocity field simulation program was developed and used to describe the laser cladding synthesis TiCp/Al composite material. A ZL104 specimen was taken as an example, to clad TiCP/Al composite by laser and to calculate the process with the developed program. Calculated results were basically coincident with those measured in the experiment.
2003(8):610-614.
Abstract:
研究了Ti-35V-15Cr(A)和Ti-25V-15Cr(B)两合金在不同温度、时间和拉应力条件下热暴露后的热稳定性能。结果表明，随着热暴露温度升高，合金性能恶化。600℃热暴露，B合金性能恶化的根本原因是表面氧化，A合金则是由于表面氧化与组织变化的共同作用。热暴露时间延长，合金塑性下降；热暴露拉应力增大，合金塑性有所提高；A合金540℃热稳定性较B合金差，两合金540℃热暴露塑性下降的主要原因来自于热暴露过程中微观组织的变化，其次为表面氧化。高钒含量A合金中的α相比低钒含量B合金中的α相更易聚集于晶界。晶界α相的析出和长大，是合金性能恶化并发生沿晶断裂的主要原因。
研究了Ti-35V-15Cr(A)和Ti-25V-15Cr(B)两合金在不同温度、时间和拉应力条件下热暴露后的热稳定性能。结果表明，随着热暴露温度升高，合金性能恶化。600℃热暴露，B合金性能恶化的根本原因是表面氧化，A合金则是由于表面氧化与组织变化的共同作用。热暴露时间延长，合金塑性下降；热暴露拉应力增大，合金塑性有所提高；A合金540℃热稳定性较B合金差，两合金540℃热暴露塑性下降的主要原因来自于热暴露过程中微观组织的变化，其次为表面氧化。高钒含量A合金中的α相比低钒含量B合金中的α相更易聚集于晶界。晶界α相的析出和长大，是合金性能恶化并发生沿晶断裂的主要原因。
2003(8):615-620.
Abstract:
用固相反应法制备了二元掺杂系列La2/3(CaxBa1-x)1/3MnO3(x=0,0.40,0.45,0.55,0.60,1.0)多晶材料;在77K～420K范围内测量了样品的电阻和磁电阻。结果表明,所制备的系列样品电阻率与温度的关系具有明显的双电阻峰结构;在T=77K～350K范围内,样品均有相似的磁电阻行为:在低温区(TTC区域,电阻率、磁电阻都随温度的升高而迅速下降,样品在高温(TC附近及T>TC区域)的这一行为可用双交换(DE)模型与非磁无序来说明。通过掺杂研究发现,掺杂量x为0.55,0.60的2种样品在室温下具有较大的磁电阻,在B=1.2T时分别达到14.5%和19.5%。
用固相反应法制备了二元掺杂系列La2/3(CaxBa1-x)1/3MnO3(x=0,0.40,0.45,0.55,0.60,1.0)多晶材料;在77K～420K范围内测量了样品的电阻和磁电阻。结果表明,所制备的系列样品电阻率与温度的关系具有明显的双电阻峰结构;在T=77K～350K范围内,样品均有相似的磁电阻行为:在低温区(T
2003(8):621-623.
Abstract:
采用真空悬浮熔炼和真空退火方法制备了Fe1-xCoxSi2-0．1at％Cu热电材料。试样的微观组织中包含大量尺寸在1μm左右的小孔和一些裂纹。输运特性测量结果表明，550K时掺杂载流子的热激发达到饱和，700K以上发生本征激发现象。实验发现Co的最佳掺杂量为lat％左右，名义组成为Fe0.97Co0.03Si2-0．1at％Cu的试样的热电性能最好。
采用真空悬浮熔炼和真空退火方法制备了Fe1-xCoxSi2-0．1at％Cu热电材料。试样的微观组织中包含大量尺寸在1μm左右的小孔和一些裂纹。输运特性测量结果表明，550K时掺杂载流子的热激发达到饱和，700K以上发生本征激发现象。实验发现Co的最佳掺杂量为lat％左右，名义组成为Fe0.97Co0.03Si2-0．1at％Cu的试样的热电性能最好。
2003(8):624-626.
Abstract:
A mathematical relationship between the strength and porosity of highly porous isotropic three- dimensional reticulated metal foams under equal- speed biaxial tension was derived.It was found that the measured properties of nickel foam,for example,were well described by the formula.
A mathematical relationship between the strength and porosity of highly porous isotropic three- dimensional reticulated metal foams under equal- speed biaxial tension was derived.It was found that the measured properties of nickel foam,for example,were well described by the formula.
2003(8):627-630.
Abstract:
A K2Ti6O13 bio ceramic coating on the surface of titanium alloy TiAlxZrx- 4Snx- 3.5Nbx- 4.5 was prepared by using an in situ kneading drying calcination synthesis technique. During emersion in a simulated body liquid the microstructure, composition of phases, bonding strength between the coating and matrix, and the bio activity of the coating were evaluated. The test results indicated that the bond strength between the coating and the matrix was high enough to resist cool and hot impact during air cooling mainly as a result of the good thermal expansion match between the coating and the matrix. Rough surfaces and small holes on the Ti alloy coating provided sites for simulated bone attachment. Soaking of the coated alloy in a simulated body liquid, encouraged the active formation of a Ca P layer with a ratio of Ca and P appropriate to human bone .
A K2Ti6O13 bio ceramic coating on the surface of titanium alloy TiAlxZrx- 4Snx- 3.5Nbx- 4.5 was prepared by using an in situ kneading drying calcination synthesis technique. During emersion in a simulated body liquid the microstructure, composition of phases, bonding strength between the coating and matrix, and the bio activity of the coating were evaluated. The test results indicated that the bond strength between the coating and the matrix was high enough to resist cool and hot impact during air cooling mainly as a result of the good thermal expansion match between the coating and the matrix. Rough surfaces and small holes on the Ti alloy coating provided sites for simulated bone attachment. Soaking of the coated alloy in a simulated body liquid, encouraged the active formation of a Ca P layer with a ratio of Ca and P appropriate to human bone .
2003(8):631-634.
Abstract:
The bending strength of three groups of samples variously oriented with respect to the length direction of the parent bulk have been measured. The bending macrofractography was carefully observed using SEM. Both the mechanical properties and the fracture behavior of sintered NdFeB permanent magnetic materials were investigated and found to be strongly anisotropic. Intergranular fracture was the primary fracture micromechanism. Cleavage fracture has been clearly observed in the microfractography of the group of bending samples whose orientation was parallel to the length direction, and the bending strength of the corresponding samples was far lower than those of the transverse- oriented samples.
The bending strength of three groups of samples variously oriented with respect to the length direction of the parent bulk have been measured. The bending macrofractography was carefully observed using SEM. Both the mechanical properties and the fracture behavior of sintered NdFeB permanent magnetic materials were investigated and found to be strongly anisotropic. Intergranular fracture was the primary fracture micromechanism. Cleavage fracture has been clearly observed in the microfractography of the group of bending samples whose orientation was parallel to the length direction, and the bending strength of the corresponding samples was far lower than those of the transverse- oriented samples.
2003(8):635-638.
Abstract:
Multilayer SiC/C composites were fabricated by tape casting and hot pressed sintering.The SiC layers and the graphite layers were found to be aligned alternately and reasonably uniformly and their interfaces were straight and well distinguishable. Mechanical properties were measured and the results showed that the strength of multilayer SiC/C composites was slighhtly less than, while its fracture toughness was higher than that of monolithic SiC. Multilayer SiC/C composites revealed a saw tooth load displacement curve. This was different from catastrophic fracture curve for monolithic SiC, and similar to the theoretical curve. Cracks propagated through multilayer SiC/C composites mainly along a step like paths, accompanied by crack branching, crack parallel propagation. Whisker like microcracks and cracks being absorbed at the weak interface were also observed by SEM. The toughening mechanism in multilayer SiC/C composites was attributed to a combination of all these effects.
Multilayer SiC/C composites were fabricated by tape casting and hot pressed sintering.The SiC layers and the graphite layers were found to be aligned alternately and reasonably uniformly and their interfaces were straight and well distinguishable. Mechanical properties were measured and the results showed that the strength of multilayer SiC/C composites was slighhtly less than, while its fracture toughness was higher than that of monolithic SiC. Multilayer SiC/C composites revealed a saw tooth load displacement curve. This was different from catastrophic fracture curve for monolithic SiC, and similar to the theoretical curve. Cracks propagated through multilayer SiC/C composites mainly along a step like paths, accompanied by crack branching, crack parallel propagation. Whisker like microcracks and cracks being absorbed at the weak interface were also observed by SEM. The toughening mechanism in multilayer SiC/C composites was attributed to a combination of all these effects.
2003(8):639-642.
Abstract:
The static fatigue and cyclic fatigue behaviour of Si3N4 ceramics in different environments (air, H2O and kerosene) were studied systematically. The results show that the stress corrosion index(n) under cyclic loading is almost the same in the various medias, and much higher than that in the same media under static loading. Mechanical cycling was deduced to introduce an additional failure mechanism that caused the cyclic fatigue life to be much shorter than static fatigue life.
The static fatigue and cyclic fatigue behaviour of Si3N4 ceramics in different environments (air, H2O and kerosene) were studied systematically. The results show that the stress corrosion index(n) under cyclic loading is almost the same in the various medias, and much higher than that in the same media under static loading. Mechanical cycling was deduced to introduce an additional failure mechanism that caused the cyclic fatigue life to be much shorter than static fatigue life.
2003(8):643-646.
Abstract:
The effects of temperature,stress and grain size on stress relaxation in the alloy TC4 have been investigated.The results show that;? the stress relaxation is sensitive to microstructure and test conditions;? increasing temperature results in higher stress relaxation rate and low relaxation limitation; ? change of initial stress also influences the stress relaxation rate and relaxation linitation; ? the fine- grain alloy has a higher stress relaxation rate than does the large- grain alloy.
The effects of temperature,stress and grain size on stress relaxation in the alloy TC4 have been investigated.The results show that;? the stress relaxation is sensitive to microstructure and test conditions;? increasing temperature results in higher stress relaxation rate and low relaxation limitation; ? change of initial stress also influences the stress relaxation rate and relaxation linitation; ? the fine- grain alloy has a higher stress relaxation rate than does the large- grain alloy.
17 Effects of Hot Extrusion on the Microstructure and Mechanical Properties of the Composite SiCW/MB15
2003(8):647-649.
Abstract:
The effects of hot extrusion on the microstructure and tensile properties of SiCw/MB15 were investigated by means of SEM,TEM and X- ray diffraction.After hot extrusion the microstructure was found to be homogeneous and with the axes of SiC whiskers are parallel to the extrusion direction the alignment of the SiC whiskers was found to improve the mechanical properties of composite.
The effects of hot extrusion on the microstructure and tensile properties of SiCw/MB15 were investigated by means of SEM,TEM and X- ray diffraction.After hot extrusion the microstructure was found to be homogeneous and with the axes of SiC whiskers are parallel to the extrusion direction the alignment of the SiC whiskers was found to improve the mechanical properties of composite.
2003(8):650-653.
Abstract:
The package of glass sealing to metal is one sort of main packages in an integrated circuit. It is constructared in the way that the insulator consisting of the glass sealed with Kovar alloy is soldered onto copper tubular base. The failure analysis of PM hybrid integrated circuit copper power shell has been made in the present paper. According to the comparision of our sample with the same sore of sealing power tube from aboard, we put forward some proposals and give the effective way to improve the quality of products.
The package of glass sealing to metal is one sort of main packages in an integrated circuit. It is constructared in the way that the insulator consisting of the glass sealed with Kovar alloy is soldered onto copper tubular base. The failure analysis of PM hybrid integrated circuit copper power shell has been made in the present paper. According to the comparision of our sample with the same sore of sealing power tube from aboard, we put forward some proposals and give the effective way to improve the quality of products.
2003(8):654-657.
Abstract:
通过三异丙氧基铽[Tb(OPr^i)3]与甲基丙烯酸甲酯(MMA)混合形成的凝胶体在偶氮二异丁腈(AIBN)引发下进行原位聚合的方法获得含铽的聚甲基丙烯酸甲酯，用红外光谱(IR)、动态机械热分析(DMTA)、热失重(TG)、荧光光谱(FS)、溶解性等手段对其进行表征。结果表明：Tb(OPr^i)3中的Tb^3 离子与MMA中的C=O存在很强的配位作用，并导致进一步交联，形成了具有交联网状结构的含铽聚合物。该聚合物具有优异的耐热性与耐溶剂性、高贮能模量、并能发射很强的Tb^3 离子的^5D4→^7F6，^5D4→^7F5，^5D4→^7F4，^5D4→^7F3跃迁的特征荧光。
通过三异丙氧基铽[Tb(OPr^i)3]与甲基丙烯酸甲酯(MMA)混合形成的凝胶体在偶氮二异丁腈(AIBN)引发下进行原位聚合的方法获得含铽的聚甲基丙烯酸甲酯，用红外光谱(IR)、动态机械热分析(DMTA)、热失重(TG)、荧光光谱(FS)、溶解性等手段对其进行表征。结果表明：Tb(OPr^i)3中的Tb^3 离子与MMA中的C=O存在很强的配位作用，并导致进一步交联，形成了具有交联网状结构的含铽聚合物。该聚合物具有优异的耐热性与耐溶剂性、高贮能模量、并能发射很强的Tb^3 离子的^5D4→^7F6，^5D4→^7F5，^5D4→^7F4，^5D4→^7F3跃迁的特征荧光。
2003(8):658-661.
Abstract:
利用微弧氧化技术，以NaOH为电解液，对Zr-4合金进行微弧表面处理，以改善抗腐蚀性能和耐磨损性能。通过电化学极化曲线测量、往复式摩擦磨损实验对Zr-4合金的抗腐蚀性能、耐磨损性能进行测试和评价。研究结果表明上述性能与基体相比有显著提高。利用SEM观察Zr-4合金微弧氧化膜厚约60μm，氧化膜分为疏松层和致密层两部分，致密层约占总厚度的1／4，与基体结合紧密。XRD分析表明微弧氧化膜由四方相和单斜相二氧化锆组成。
利用微弧氧化技术，以NaOH为电解液，对Zr-4合金进行微弧表面处理，以改善抗腐蚀性能和耐磨损性能。通过电化学极化曲线测量、往复式摩擦磨损实验对Zr-4合金的抗腐蚀性能、耐磨损性能进行测试和评价。研究结果表明上述性能与基体相比有显著提高。利用SEM观察Zr-4合金微弧氧化膜厚约60μm，氧化膜分为疏松层和致密层两部分，致密层约占总厚度的1／4，与基体结合紧密。XRD分析表明微弧氧化膜由四方相和单斜相二氧化锆组成。
2003(8):662-665.
Abstract:
介绍了负载不同晶型TiO2薄膜电极的制备，并研究了聚乙二醇加入量、活化条件等对不同晶型、不同形貌、不同粒径纳米TiO2薄膜电极的光电催化活性的影响。结果表明：聚乙二醇加入量有一最佳值；且纳米级锐钛矿型TiO2和金红石型TiO2分别经600℃和400℃煅烧后，光电催化性能最好；粒径越小催化活性越高．当粒径小于25nm时，可显示出量子尺寸效应。
介绍了负载不同晶型TiO2薄膜电极的制备，并研究了聚乙二醇加入量、活化条件等对不同晶型、不同形貌、不同粒径纳米TiO2薄膜电极的光电催化活性的影响。结果表明：聚乙二醇加入量有一最佳值；且纳米级锐钛矿型TiO2和金红石型TiO2分别经600℃和400℃煅烧后，光电催化性能最好；粒径越小催化活性越高．当粒径小于25nm时，可显示出量子尺寸效应。
22 Preparation of Nanosized Yttria Stabilized Zirconia Powders by Phase- Transfer- Separation Process
2003(8):666-669.
Abstract:
相转移分离法是1种新颖的陶瓷粉末制备方法,能迅速有效地从溶液中分离出高度亲水的氢氧化物沉淀,从而达到液-固分离的目的。本研究首次用该方法制备了8mol%氧化钇稳定的氧化锆(8YSZ)超细粉末。合成的8YSZ粉末具有赝立方结构,平均粒径在20nm～30nm左右。粉末中Na和Cl的含量分别为7.05×10-6和1.414×10-4。工艺中的石油醚可以回收,回收率为80%。可以认为,相转移分离法是1种有广阔应用前景的超细陶瓷粉末制备方法。
相转移分离法是1种新颖的陶瓷粉末制备方法,能迅速有效地从溶液中分离出高度亲水的氢氧化物沉淀,从而达到液-固分离的目的。本研究首次用该方法制备了8mol%氧化钇稳定的氧化锆(8YSZ)超细粉末。合成的8YSZ粉末具有赝立方结构,平均粒径在20nm～30nm左右。粉末中Na和Cl的含量分别为7.05×10-6和1.414×10-4。工艺中的石油醚可以回收,回收率为80%。可以认为,相转移分离法是1种有广阔应用前景的超细陶瓷粉末制备方法。
2003(8):670-673.
Abstract:
利用扫描电镜(SEM)、透射电镜(TEM)、电子探针(EPMA)、能谱(EDS)和X射线衍射(XRD)技术研究了硅对定向凝固Ni3Al基合金IC6A微观组织的影响。结果表明在IC6A合金中添加0．10％～0．20％Si(质量分数，下同)会使合金的枝晶间区析出块状的Mo1.24Ni0.76相和Mo6(Ni0.75Si0.25)7相，当硅的添加量达到0．30％时，合金的枝晶间区除了析出这两种相外，还有针状的δ-NiMo相析出。这相的析出不利于合金的高温持久性能，它们的硬度较大，只能通过孪晶的方式变形。硅有利于提高IC6A合金的高温抗氧化性能，而对合金的抗腐蚀性能和瞬时拉伸性能无明显影响。
利用扫描电镜(SEM)、透射电镜(TEM)、电子探针(EPMA)、能谱(EDS)和X射线衍射(XRD)技术研究了硅对定向凝固Ni3Al基合金IC6A微观组织的影响。结果表明在IC6A合金中添加0．10％～0．20％Si(质量分数，下同)会使合金的枝晶间区析出块状的Mo1.24Ni0.76相和Mo6(Ni0.75Si0.25)7相，当硅的添加量达到0．30％时，合金的枝晶间区除了析出这两种相外，还有针状的δ-NiMo相析出。这相的析出不利于合金的高温持久性能，它们的硬度较大，只能通过孪晶的方式变形。硅有利于提高IC6A合金的高温抗氧化性能，而对合金的抗腐蚀性能和瞬时拉伸性能无明显影响。
24 Mechanical and Electrical Properties of Reaction-formed Joints in Silicon Carbide Ceramic Materials
2003(8):674-676.
Abstract:
Joints between reaction bonded silicon carbide and recrystallized silicon carbide have been prepared by a reaction forming method. The microstructure in the joint area and the fracture morphology were observed by optical microscopy and scanning electron microscopy respectively. The mechanical and electrical properties of the reaction formed joints were evaluated. This study suggested that a good contact interlayer could be formed between the joint and monolithic material by the described method. The flexural strength and electrical resistivity of the silicon/ silicon carbide bulk material were not affected significantly by the presence of the reaction formed joints. It is important to optimize the joining layer microstructure and composition in order to obtaining high performance joints.
Joints between reaction bonded silicon carbide and recrystallized silicon carbide have been prepared by a reaction forming method. The microstructure in the joint area and the fracture morphology were observed by optical microscopy and scanning electron microscopy respectively. The mechanical and electrical properties of the reaction formed joints were evaluated. This study suggested that a good contact interlayer could be formed between the joint and monolithic material by the described method. The flexural strength and electrical resistivity of the silicon/ silicon carbide bulk material were not affected significantly by the presence of the reaction formed joints. It is important to optimize the joining layer microstructure and composition in order to obtaining high performance joints.
